EXTRACELLULAR PRODUCTION OF HUMAN HEPATITIS-B VIRUS PRES2 ANTIGEN AS HYBRID PROTEINS WITH BACILLUS-SUBTILIS ALPHA-AMYLASES IN HIGH-SALT-CONCENTRATION MEDIA

To produce PreS2 antigen of human hepatitis B virus extra-cellularly i n Bacillus subtilis, it was fused with the COOH-termini of B. subtilis alpha-amylases of 522 (Amy(+)), 467 (Amy(+)) and 443 (Amy(-)) amino a cids. Among them, alpha-amylase-A467, which has 467 amino acids, was a relatively stable carrier when the cells were cultured in Luria-Berta ni (LB) medium. The alpha-amylase-A443-PreS2 hybrid protein (Amy(-)) w as quickly degraded. The alpha-amylase-A522-PreS2 hybrid was most effi ciently produced when a B. subtilis transformant of a protease-super-d eficient mutant was cultured in the presence of 0.5 M sodium sulphate. The production of A522-PreS2 hybrid protein under such conditions rea ched 5-10 mg/l and was eight, and 200-500 times higher than those obta ined by the transformants of an alkaline/neutral protease-deficient mu tant of B. subtilis, and a wild-type strain, in LB medium, respectivel y.